Solar panel defects: Hot spots, snail trails, and more

Solar panels are incredibly reliable and have proven to be great for the environment and a superb investment. Their reliability comes from the fact that they are solid-state electronic devices, meaning that there are no moving parts. This nearly eliminates the risk of mechanical failure and allows panels to be extremely low maintenance for long periods. However, nothing is perfect, and solar panels can develop defects throughout their lifetime. We've put together a list of the most common problems that can occur with your solar system.

Lamination of solar panels keeps the solar cells protected by vacuum sealing and fusing the solar cell, the glass sheet, and the back sheet. While these seals are typically extremely secure, if the lamination process is not done correctly, delamination–the separation of the bond between these components–can occur. Delamination typically starts at the panel's edge and gradually works inward. Without a secure seal, moisture and air can enter the system, causing corrosion and substantially reducing panel performance. If you see dark spots on your panels, this could be a sign that your panels are undergoing delamination, and you should contact your installer for an inspection.

Micro cracks are tiny tears in solar cells stemming from haphazard shipping and installation or defects in manufacturing. While these micro-cracks do not lead to immediate energy production loss, weather changes, and general wear and tear can contribute to their growth over time and make them a more significant issue. Hiring an experienced and trustworthy installer, such as one on the EnergySage Marketplace, will help lessen the risk of micro-cracks during installation.

Hot spots, one of the most common issues with solar systems, occur when areas on a solar panel become overloaded and reach high temperatures relative to the rest of the panel. When current flows through solar cells, any resistance within the cells converts this current into heat losses. Imperfections in meetings, such as cracks, poor soldering, or the accumulation of dirt, can cause this resistance to increase in a concentrated area, causing a hot spot. It's essential to deal with these immediately if they appear because, if left unchecked, they can cause degradation of your system or even render it irreparable.

Occasionally, solar panels can develop small brown lines on the surface, termed "snail trails," because they give the appearance that snails have passed over the panel. Snail trails typically appear after only a few years and can have multiple causes, often attributed to lower-quality panels. Defects in these panels can allow moisture to enter through the back sheet, causing oxidation between silver paste, a key material used in manufacturing, and the encapsulation material. This reaction causes the front of the panel to break down chemically, reducing the system's performance and ultimately causing it to fail prematurely. Snail trails are often associated with micro-cracks and can create hot spots. Purchasing reputable panels can substantially lower your risk of snail trails.

Potential Induced Degradation, or PID, occurs due to the high voltage difference between the grounded glass sheet and the solar cells. When this happens, the primary power circuit can produce a partial voltage discharge, which reduces the performance and accelerates the aging of the panel. PID generally occurs shortly after solar systems are installed and can be exacerbated by long string connections, hot temperatures, and high humidity. Fortunately, if spotted early, solar professionals can help reverse or prevent this problem.

Occasionally, poor installation of your solar system can lead to electrical issues. Problems such as loose wiring or wiring damage caused by corrosion or oxidation can ultimately lower your system's production. If you think your system may be affected by electrical issues, contacting your installer is best. Assessing the situation yourself will put you at unnecessary risk that your installer or a licensed electrician is trained to handle.

Inverters help to convert solar energy into alternative current usable in your home. While the panels usually last between 25 and 30 years, inverters are slightly less durable. They typically need to be replaced every 10 to 15 years for string inverters and up to 25 years for micro inverters. Check these if you notice an issue with your panels' electricity production around these times.

Finally, while you may enjoy your neighborhood wildlife, they can sometimes be a nuisance in your solar system. Birds and squirrels are some of the biggest culprits for causing problems. By building nests in the space between your panels and your roof, they can wreak havoc on wiring and other sensitive electronics. Critter guards are a simple and effective way to protect against this problem.

Photovoltaic systems are amazingly reliable and require minimal maintenance throughout their lifetimes. Still, like any other electrical device, they're vulnerable to manufacturing defects and general wear and tear. Typical costs to repair these kinds of issues range from about $100 to $350, although costs can vary depending on the severity of the problem. If you notice any of these issues, contact your installer to get your system inspected as soon as possible. Using reputable installers and equipment can significantly lower your risk of experiencing many of these problems. Checking your panels regularly and keeping them clear of debris should provide dependable, clean energy for decades.